ABSTRACT
Lithium has many actions on thyroid physiology. The most important clinically relevant action is the inhibition of thyroid hormone release. This may result in the development of goiter and hypothyroidism. Independent effects on the hypothalamic-pituitary-thyroid axis and the receptor-mediated mechanism of thyroid hormone action may contribute to this picture. The effect of lithium on inhibition of cyclic AMP-mediated cellular events and its inhibitory effect on the phosphoinositol pathway help to explain the intracellular disturbances, but the full mechanisms are still not clear. The immunological influence of lithium on thyroid antibody concentrations leads to a more rapid onset of thyroid autoimmunity characterized usually by goiter and hypothyroidism but possibly also a state of hyperthyroidism in some cases.
